The present invention relates to a washing machine having a spin-extracting function.
In particular, the present invention relates to a drum-type washing machine having a drum rotatable about a horizontal axis, or a whirlpool-type washing machine having a wash-and-extraction tub rotatable about a tilted axis.
In general, a drum-type washing machine has a cylindrical basket drum rotatable about a horizontal axis. When the drum is rotated at high speed with the wet laundry loaded therein, the water held by the laundry is extracted and scattered by a centrifugal force. One problem concerning the extraction process is that abnormal vibration and/or noise arises when the drum is rotated at high speed if the mass distribution around the rotation axis is unbalanced as a result of uneven distribution of the laundry on the inner peripheral wall of the drum.
Various proposals have been made for solving the above-described problem. For example, UK Patent Publication Nos. GB2271172 and GB2138029 disclose washing machines having plural water-holding chambers or compartments (those utilizing the inner space of baffles, for example) located around the rotation axis of the drum. By this washing machine, water is supplied into one of the chambers located at or close to a position opposing to the position of the eccentric load due to the uneven distribution of the laundry, whereby the balance of the drum is corrected as a whole. By this washing machine, the eccentricity of the drum as a whole can be lessened in whatever manner the laundry is distributed on the inner peripheral wall of the drum.
Regarding the operation of the above washing machine, however, it is necessary to selectively supply a certain amount of water into proper one or a few water-holding chambers while the drum is rotating. For that purpose, one of the washing machines is provided with plural water supply pipes in the rotation shaft for conveying water to each of the water-holding chamber. Such a water-supplying mechanism, however, is not practical because the structure is very complicated and costly.
In view of the above problem, one object of the present invention is to propose a washing machine having a simple-structured balancing mechanism whereby an unbalance of the drum is cancelled as a whole by adding a weight to the drum for balancing an eccentric load wherever the eccentric load is located on the inner peripheral wall of the drum.
Thus, in the first aspect of the present invention, the washing machine has a basket-like extraction tub rotatably mounted in an outer tub, and the extraction tub is rotated at a high speed with the laundry loaded therein to extract a washing liquid (water or solvent) from the laundry by a centrifugal force. Further, according to the first aspect of the invention, the washing machine includes:
a plurality of water-holding chambers provided around a rotation axis of the extraction tub for holding water inside by the centrifugal force;
a water supplier for supplying water to the water-holding chambers without contacting them;
a rotation controller for controlling a motor for driving the extraction tub;
an eccentric load detector for detecting a position of an eccentric load due to an uneven distribution of the laundry in the extraction tub; and
an operation controller for controlling the water supplier and the rotation controller: to fill the water-holding chambers with a substantially equal amount of water while rotating the extraction tub at a preset speed; and to temporarily reduce the speed of the extraction tub at a time point determined corresponding to the position of the eccentric load to decrease the amount of water held in one or some of the water-holding chambers located at or close to the position of the eccentric load.
The problem of the above conventional washing machine is that water should be selectively and properly supplied to one or a few water-holding chambers according to the position of the eccentric load. According to the first aspect of the present invention, on the other hand, the water-holding chambers are first filled with substantially equal amounts of water, and then the amount of water in one or a few water-holding chambers are selectively reduced by discharging a part of the water. Even while the drum is rotating, it is relatively easy to supply water equally to all the water holding chambers of the drum. The speed of the drum is determined so that the water is held in the water-holding chamber by the centrifugal force. It is possible to let the water in a certain water-holding chamber or chambers spill out by controlling the speed of the drum so that the centrifugal force is decreased.
The washing machine works as follows. When all the water-holding chambers are empty, the extraction tub is rotated at a speed where the centrifugal force acting on the laundry is greater than the gravitational force. Then, the eccentric load detector detects the magnitude and position of the eccentric load due to the uneven distribution of the laundry. When the eccentric load is large, the operation controller rotates the extraction tub at a speed where the centrifugal force acting on the water held in the water-holding chamber is greater than the gravitational force and supplies an adequate amount of water into each of the water-holding chambers. By designing the water-holding chamber to have the same capacity, all the waterholding chambers can contain with almost equal amounts of water when the chambers are fully charged. It is hereby probable that the extraction tub has a large eccentric load. In this case, in order to prevent a large vibration, it is preferable to set the speed as low as possible so long as the above condition is met.
After filling all the water-holding chambers with water, the operation controller commands the rotation controller to temporarily reduce the speed so that a part of the water in the water-holding chamber located at or close to the detected position of the eccentric load spills out. In detail, the speed is reduced at a time point where such chamber (the target chamber) comes to the top of the rotation. As the amount of water in the target chamber decreases, the weight of water at the position decreases, and the eccentricity of the extraction tub decreases as a whole.
In a mode of the above washing machine, the extraction tub is a drum rotatable about a horizontal axis. In this mode, the water-holding chambers may be box-like members located around the horizontal axis. Each water-holding chamber has an opening in its inward face, and the water supplier discharges water to the opening of one of the water-holding chambers which is then at the bottom of the rotation.
While the drum is rotated at a speed where the centrifugal force acting on the water in the water-holding chamber is greater than the gravitational force, the water supplier discharges water to a water-holding chamber then passing the bottom of the rotation. As the rotation proceeds, the water-holding chamber is lifted, and the water inside is pressed onto the outer wall of the inner space of the chamber by a centrifugal force. Thus, the water is prevented from spilling out from the water-holding chamber even when the opening is directed downward. When the drum is decelerated, the water held by the water-holding chamber then located at the top of the drum at the time point spills out from the opening. Thus, the amount of water held by any of the water-holding chambers can be decreased as desired.
In another mode of the above washing machine, the extraction tub is constructed as a wash-and-extraction tub having a pulsator at its bottom. The wash-and-extraction tub and the pulsator are rotatable about a common tilted axis. In this mode, the water-holding chamber may be constructed as a ring-shaped hollow body placed at the upper end of the wash-and-extraction tub. The hollow body is partitioned into a plurality of chambers each of which has an inlet opening in its upper face and an outlet opening in its lower face of the inner part of the hollow body. The water supplier pours water through the inlet opening into the chamber.
While the drum is rotated at a speed where the centrifugal force acting on the water in the water-holding chamber is greater than the component of gravitational force acting on the water in the radial direction of the ring-shaped hollow body, water is discharged from the water supplier. The water enters the water-holding chamber passing at the water-discharging point at the time point. In the water-holding chamber, the water is pressed onto the inner wall of the chamber by the centrifugal force. Thus, the water is prevented from being discharged from the outlet opening. When the tub is decelerated, the water held by a water-holding chamber that is located at the top of the rotation of the tub is spread by the gravitational force and is discharged from the outlet opening. Thus, the amount of water held by any of the water-holding chambers can be decreased.
In the second aspect of the present invention, the washing machine has a basket-like extraction tub rotatably mounted in an outer tub, and the extraction tub is rotated at a high speed with the laundry loaded therein to extract a washing liquid from the laundry by a centrifugal force. Further, according to the second aspect of the invention, the washing machine includes:
a balancer constructed as a ring-shaped hollow body with a liquid contained therein, where the hollow body is placed surrounding the rotation axis of the extraction tub and is partitioned into a plurality of compartments communicating with each other via a passage extending along the inner circumference of the hollow body;
a rotation controller for controlling a motor for driving the extraction tub;
an eccentric load detector for detecting a position of an eccentric load due to an uneven distribution of the laundry in the extraction tub; and
an operation controller for controlling the rotation controller: to fill the compartments of the balancer with a substantially equal amount of the liquid by rotating the extraction tub at a preset speed; and to transfer a part of the liquid held in one of the compartments to another compartment by temporarily reducing the speed of the extraction tub at an appropriate time point corresponding to the position of the eccentric load.
According to the second aspect of the present invention, the washing machine is equipped with a balancer constructed as a ring-shaped hollow body in which a plurality of compartments are formed communicating with each other at the inner side. At first all the water-holding chambers are equally filled with water, and then a part of the water is transferred from one or plural water-holding chambers to one or some of the other water-holding chambers according to the eccentric load. By such a construction, there is no need to supply water from outside into the water-holding chamber.
The operation controller first controls the rotation controller to rotate the extraction tub at or close to a speed where the centrifugal force acting on the liquid in the compartment is substantially balanced with the gravitational force. In this process, the liquid moves from one compartment to another because the centrifugal force is not large enough to press the liquid onto the outer wall of the inside of the compartments. As a result, the compartments are filled with a substantially equal amount of the liquid. Under such a condition, the eccentric load of the balancer can be ignored, so that the eccentric load detector detects the magnitude and position of an eccentric load due only to an uneven distribution of the laundry. When the eccentric load is large, the operation controller commands the rotation controller to temporarily reduce the speed of the extraction tub so that a part of the liquid held by a first compartment located at or close to the eccentric load is made to flow out of the first compartment into a second compartment in opposition to the first compartment. That is, for example, the speed is temporarily reduced at a time point when a target compartment (first compartment) arrives at the top of the rotation. As a result of transferring the liquid as described above, the weight balance of the liquid changes, so that the eccentricity of the extraction tub as a whole decreases.
As in the first aspect of the invention, the washing machine according to the second aspect of the present invention may be constructed either as a drum-type washing machine having a drum rotatable about a horizontal axis or as a whirlpool-type washing machine having a wash-and-extraction tub rotatable about a tilted axis.
In comparison to the above-mentioned conventional washing machines, the construction of the washing machine according to the present invention is simplified because there is no need to use a complicated water-supplying mechanism for selectively supplying a proper amount of water to the water-holding chambers. Further, according the present invention, even when the laundry is unevenly distributed on the inner peripheral wall of the extraction tub, the balance of the extraction tub can be corrected by decreasing the amount of water held by one or a few water-holding chambers located at or close to the position of the eccentric load. Thus, the balance is corrected within a very short time period.